Earlier on Thursday, the Russian Defense Ministry confirmed that Syrian government troops had gained full control of the Douma enclave in Eastern Ghouta, 10km from Damascus.
United States president Donald Trump has told Russian Federation to "get ready" for missiles to be fired at Syria, using Twitter to lambast Russian Federation for being "partners with a Gas Killing Animal who kills his people and enjoys it".
Russian Federation does not seek praise, only genuine cooperation in the fight against terrorism, Zakharova said, commenting on US President Donald Trump's recent tweet. "You shouldn't be partners with a Gas Killing Animal who kills his people and enjoys it!"
Peskov wouldn't say if Moscow could use a Russia-U.S. military hotline to avoid casualties in a case of a U.S. blow, saying only that "the hotline exists and has remained active".
According to the sources, the specific response being considered in the event of US military action against Syria is Japan's "support for the USA resolve to fulfill its responsibility to prevent the use of chemical weapons".
Meanwhile, the Assad regime denies using chemical weapons and called the images from the attack fake.
Mr. Mattis' remarks at a House Armed Services Committee hearing followed a series of Trump tweets this week that initially indicated he was committed to bombing Syria but later suggested he was awaiting further advice and assessment.
Russia, she alleged, holds some responsibility in the fact that they had guaranteed that Syria wouldn't use chemical weapons again, which they did. Russian Federation and Syria have been calling for the worldwide investigation of the alleged attack.
"And announcing military actions over Twitter is the height of irresponsibility and contradicts the President's own previous commitment never to disclose America's plans publicly", Markey said.
Mr. Mattis said options would be discussed with Mr.Trump at a meeting of his National Security Council on Thursday afternoon.
After Ms. May met with her Cabinet, a spokesperson issued a statement saying it is highly likely that Syria's President Bashar Assad was responsible for Saturday's attack that killed dozens outside Damascus.
Earlier in the day, Bashar al-Jaafari, Syrian ambassador to the United States, said in NY that two investigating teams from the OPCW were scheduled to arrive in Syria within the next 24 hours.
Rep. Adam Smith, the ranking Democrat on the House Armed Services Committee, said he sees no legal justification for a US strike in Syria, absent explicit authorization by Congress. The fact-finding mission of the OPCW is to start their work in Douma on Saturday.